Measuring the Down-Force

By Marie Redding
Freelance Writer

The down-force measurement can be another useful tool in the validation process, because it helps to ensure repeatable results, according to John Abraham, president, Atlas Vac (Cincinnati).

When one package is sealed well by using a formula that incorporates a certain down-force measurement, the sealing process can be more easily replicated for different size packages, or on different machines. 

“Knowing the required down-force per square unit surface area from a previous project enables the next project to initially start at a high probability set point, requiring far less experimentation. Then, you can work from there to develop a workable set of production parameters to fully validate,” explains Abraham. If the down-force isn’t known, traditionally, an engineer would experiment with a wide range of values for dwell time, temperature, and psi to statistically map out results and identify the best operational setting points, which takes a lot longer.

The down-force affects the quality of the seal. At the same pressure, two similar machines may put out a significantly different level of force. Variations are due to age of the equipment, as well as other factors.

A number of years ago, Atlas Vac was the first supplier to patent its “Force Sensing” system for digitally measuring the down-force that is applied to a seal. This option can be incorporated into any of the company’s sealers, which are often used for medical device trays.

Measuring the down-force can be useful when a large company needs to harmonize its manufacturing processes at different factories. “A customer once said he needed a solution like this, because using a validated process document with temperature, psi, and time measurement isn’t enough to replicate a validatable seal for the same package on a machine in a different factory halfway around the world,” says Abraham.

According to Abraham, many of its customers are now realizing the significance of knowing the down-force measurement. “Whenever I’m performing an installation qualification, the question of force is always raised by a packaging engineer,” he says.
Abraham compares the down-force to measuring the speed of a car. “It’s not how hard you are pressing on the gas pedal, it’s the results on the laser or radar gun that count,” he says.